Vacuum tube with built-in tuned inductance



Jan 24, 1950 M. T. WILDE VACUUM TUBE WITH BUILT-IN TUNED INDUCTANCE 5 She'ets-Sheet 1 Filed Feb. 5, 1945 INVENTOR. mow/v 2' am a:

Jan. 24, 1950 M. T. WILDE VACUUM TUBE WITH BUILT-IN TUNED INDUCTANCE 5 Sheets-Sheet 2 Filed Feb. 5, 1945 Qfb:

. INVENTOR. MV/fd/V 71' W/ZZZE WW 9, LAW,

Jan. 24, 1950 M; T. WlLDE 2,495,302

VACUUM TUBE WITH BUILT-IN TUNED INDUCTANCE Filed Feb. 5, 1945 5 Sheets-Sheet 3 IN VEN TOR. N/EOA/ 7. W/L 95 BY W X/M A Jan. 24, 1950 M. T. WlLDE VACUUM TUBE WITH BUILT-IN TUNED INDUCTANCE 5 Sheets-Sheet 4 Filed Feb. 3, 1945 INVENTOR. fiWPO/V I l V/ZJ/f Patented Jan. 24, 1950 UNITED STATES PATENT OFFICE VACUUM TUBE WITH BUILT-IN TUNED INDUCTANCE (Granted under the act of March 3, 1883, 18 amended April 30, 1928; 3'70 0. G. 757) 1 Claim.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to electronic tubes for use in radio work and more particularly to such a tube containing a variable transformer and other required circuit components so that the variable components can be tuned from outside of the tube, and a tube which provides, for example, a complete intermediate frequency stage or the like for use in receiver circuits.

The objects of the present invention comprise the provision of an improved evacuated radio tube that contains a desired group of tube elements, and adjustable inductance element that preferably may be permeability tuned from outwardly of the tube and other required components therein; an evacuated radio tube that is adapted to provide a substantially complete intermediate frequency or other desired stage in a radio receiver circuit and that is readily replaceable upon its failure; a tube that contains a desired group of circuit components that are protected against functional irregularities arising from their environment such as moisture content, of salt spray in, or the presence of conductive metal particles in, the ambient air; an evacuated radio tube that contains a desired plurality of circuit components within its sealed envelope and that operates at a constant temperature and without drift after the tube arrives at its working temperature, and that will operate as satisfactorily in the arctic as it will in the tropics, since the variable component of the tube is readily changed by being adjustable to compensate for the temperature at which the tube is required to operate; an improved multiple component tube that can be quickly and easily brought into alignment with the remainder of a circuit from outwardly of the tube; and a multiple component containing, evacuated radio tube that is adapted for large scale production with a minimum of operations and of cost and that minimizes adjustment and operative problems.

With the above and other objects in view that will be apparent to those who are informed in the matter of evacuated. radio tubes from the following discussion, illustrated embodiments of the present invention are shown in the accompanying drawings, wherein:

Fig. 1 is an elevational view, partly in section and partly schematic, of an electronic tube that contains a double triode and a variable coaxial transformer and that embodies the present in vention;

Fig. 2 is an elevational view, partly in section and partly schematic, of an electronic tube that contains a single group of tube elements and an externally adjustable coaxial variable transformer as parts thereof;

Fig. 3 is an elevational view, partly in section and partly schematic, of a double triode tube in which variable co-planar inductors can be adjusted from the end of the tube that is remote from its base;

Fig. 4 is an elevational view that is partly in section and partly schematic of an electronic tube, wherein the inductance coils are co-planar and adjustable from the side of the tube and are separated by a screening partition from the tube elements thereof;

Fig. 5 is an elevational view, that is partly in section and partly schematic, of a further modification of the tube that is shown in Fig. 1.

The first form of electronic tube that is shown in the accompanying drawings comprises a pref erably evacuated continuous envelope within which the component parts of the tube are disposed. An input terminal I, to which a clip from the secondary coil of a transformer, not shown, or other suitable connection may be applied, is mounted on an envelope 3 to provide the tube with an electric signal of radio frequency, intermediate frequency, or the like.

The input terminal I feeds signal to a grid 2 of a first triode within the evacuated tube en velope 3 that is of glass or the like, and that is mounted in the usual way on a base 4. The cathode 5 of the first triode terminates thru the tube base 4 in a contact pin 6. The cathode 5 may be connected thru a cathode bias resistor. not shown, disposed within the tube and thru the contact pin 6 to ground. One end of the cathode heater I also is connected thru the base 4 by a contact pin 8 and is connected to ground or to the cathode 5, the connection not being shown for simplicity, as is usual in circuits of this type. A shield I0 is provided for the first triode. The various component parts within the envelope 3, are supported in any usual manner, as upon stems, not shown, that extent upwardly from the base 4 or that are embodied in the tube envelope 3.

The circuit from the plate 9 of the first tri d passes thru an inductor, such as a solenoid or coil M, to a contact pin i5 tha in a superheterodvne circuit, would be connected to the positive post of a B power supply to provide the positive plate voltage for the first triode of the tube. The solenoid I4 is mounted inside of the tube envelope 3 and is variably tuned from outside thereof in any desired manner. The solenoid i4 is preferably supported by being wound around a hollow cylindrical insulating tube It that preferably is sealed upwardly and that has its lower end sealed to the envelope 3, thru which it opens downwardly, so that the evacuation of the envelope 3 is maintained intact throughout the life of the tube. The solenoid i4 is permeability tuned and preferably by means of a powdered iron core I! that is adjustably mounted with respect to the solenoid M, as by being movable axially thereof, or the like. An opening thru the base 4 permits entrance of the core l! within the tube I5. In the construction shown, the core I! is molded upon a screw it that threads thru a nut I 9 that is secured in the open end of the bore of the tube I6 against a shoulder in, and adjacent the open end of, the bore therein.

A flange 20, on the screw l8 and adjacent the unattached end thereof, limits the penetration of the core 27 within the coil [4 and also prevents its being driven thru the closed end of the tube H5. The unattached end of the screw I8 is provided with a tool engageable means, such as the screw driver slot shown, or the like.

The solenoid i4 is inductively coupled as primary to another solenoid or coil 24 as secondary that is also disposed within the evacuated interior of the envelope 3. The solenoid 24 is positioned around a cylindrical depression 25 in the envelope 3 so that the coils l4 and 24 are substantially in axial alignment with respect to each other. The secondary coil 24 is variably tuned by the relative position therein of a powdered iron core 26. The core 26 is mounted on an end of a screw 21 that threads thru a nut 28. The nut 28 rests upon a shoulder in the bore of the depression 25 near the upper end thereof. The nut 28 preferably is engaged by a flange 29 on the screw 2! to limit the depth in the depression 25 to which the core 26 may be driven by the screw 21. The nuts i9 and 28 preferably are of fibroid, a plastic, or the like, and are preferably secured in place by cement. The screw 21 has a screw driver slot 30, or the like, at its free end for use in moving the core 25 with respect to the coil 24. The coils l4 and 24 preferably are shunted by capacitors 3i and 32, respectively, for assisting in bringing the coils to resonance at required frequencies.

One end of the secondary coil 24 is connected thru the envelope 3 and the base 4 to a pin 33 that serve as a grid return contact that may be connected to ground direct or thru an impedance.

When the impedance, not shown, is used it may be positioned within the envelope 3 if preferred. The opposite end of the secondary coil 24 feeds inducted radio energy to a grid 34 of a second triode within the evacuated interior of the envelope 3. A cathode 35 of the second triode is connected thru the envelope 3 and the tube base 4 to a contact 36. A heater 3? in the second triode has a base contact 38 and is wired in series or in parallel, as preferred, with the first triode heater 1. Both heaters l and 37 may be separately supplied with power thru base contacts, if preferred. The second triode preferably also is provided with a shield39 which is connected to ground or to the cathode 35 when the tube is in circuit. The plate 4%] of the second triode is connected to an output terminal 4| for the tube.

The tube described above is illustrative of a double triode assembly for use in intermediate frequency amplification. The number of elements within the tube may be modified or increased, where preferred, within the scope of the present invention, such as the replacing of one or more of the triodes with a diode, a pentode or the like, as required. The omission of the described tube elements from the evacuated envelope 3 for limiting the construction to the protection of the adjustable inductance coils l4 and 24 only is also within the scope of the present invention. The coils l4 and 24 are preferably of enamel coated wire that is reenameled or impregnated after winding to minimize the presence of flaws and cracks in the original enamel coat caused by the winding operation. Where desirable the coil supports l6 and 25 may be continuous axially of the envelope 3 and the powdered iron cores I! and 26 replaced by a single core that is adjustable with respect to the coils l4 and 24 in any preferred usual manner in lieu of the screws I8 and 21. Preferably the tubes that are shown herein are individually shielded externally, not shown, in usual manner when installed in a circuit to isolate the tuned transformer within each individual tube.

In operation as in inductively coupled intermediate frequency stage in a receiver superheterodyne circuit, connection is made from the signal output from the secondary winding of a prior transformer, not shown to the input contact l of the present tube. The received signal on the grid 2 appears on the plate 9 of the first triode and passes thru the primary solenoid winding l4 which supplies B plate voltage to the plate 9 of the first triode. The coil I4 is adjusted to the frequency of the incoming signal by varying the penetration therein of the core I? by rotation of the screw [8 by which operation the coil I4 is permeability tuned. The coil 24 is adjusted to the same frequency and is permeability tuned by the rotation of the screw 21 to control the disposition of the core 26 with respect thereto.

The signal that is induced from the solenoid l4 into the solenoid 24 is impressed on the grid 34 of the second triode and appears on the plate 40 thereof from which it leaves the tube thru the output terminal 4| thereof. In this manner the tube that is shown in Fig. 1 provides one stage in a receiver circuit.

The tube that is shown in Fig. 2 of the drawings comprises a unit intermediate frequency stage that may be introduced into a superheterodyne receiver circuit, singly or in greater numbers, as preferred. Two tubes of the type that is shown in Fig. 2 may be used as two additional stages in an I. F. circuit when the output terminal 4| of the tube that is shown in Fig. 1 is connected to an input terminal of the tube that is shown in Fig. 2, and another tube of the type shown in Fig. 2 is connected in series to the output terminal 64 thereafter.

The input terminal 45 introduces input intermediate frequency signal to a primary solenoid 46 that is disposed within the evacuated envelope 4'! of the tube. As in the previously described constructions, the solenoid 4B is mounted upon a cylindrical depression 48 that extends downwardly from the top wall of the sealed envelope 41. The end of the solenoid 46 that is remote from the input contact 45, terminates thru the envelope 4'! and the tube base 44 in a pin 42 that, when the tube is in circuit, is connected to a B plus power supply to provide plate voltage for the preceding tube, such as for the plate 46 or the like of the tube that is shown in Fig. l. The primary solenoid 46 is inductively coupled to a secondary solenoid 49 that is mounted upon a hollow cylindrical support 56 that opens thru the envelope 4! and the base 44 of the tube. The solenoids t6 and 49 are preferably substantially in axial alignment. The solenoid 4% is permeability tuned adjustably by the rotation of a screw 5i that threads thru a nut 52 to vary the insertion in the solenoid 4B of a preferably owdered iron core 53 that is mounted on the inner end of the screw 55. The solenoid 49 is permeability tuned by means of the pewdered iron core 55 that is mounted on a screw 55 that threads thru a nut 5'1. The nuts 52 and 51 preferably are secured in the bores of the supports 43 and 50, respectively, by cement or the like. Capacitors 58 and 59, where needed, shunt the solenoids 46 and 49, respectively. Since both leads of the solenoid 46 extend to outwardly of the tube, the capacitor 58 may be disposed outwardly of the evacuated envelope 4? if preferred.

One end of the secondary solenoid 49 terminates thru the envelope 4'! and the base 44 in a contact pin 43 that, when the tube is in circuit, provides the grid return for the triode within the envelope Al. The opposite end of the coil 49 leads to a grid 66 of the triode within the tube envelope 4?. The cathode 5! of the triode is connected by a lead thru the envelope 4'! and the base 44 of the tube to a pin 65. A heater element 62 receives its electrical energy thru a pair of contacts 66 and 61 that extend thru the envelope 41 and the base 44 of the tube. The plate 53 of the triode within the evacuated envelope 4'! is connected to the output terminal 64 of the tube. The triode within the tube that is shown in Fig. 2 may be replaced by another group of tube elements, such as those of a pentode or the like, and the resultant tube is within the scope of the present invention.

In operation, signal entering the tube thru the input terminal 45 is applied to the coil 46 and is inductively coupled from the tuned solenoid 46 to the tuned solenoid 49 and from the solenoid 49 signal passes to the triode grid 80. From the plate 63 signal passes to the output terminal 54. In all of these circuits elements of secondary importance have been omitted for purposes of simplicity in presentation.

Another modification in the present invention is shown in Fig. 3 of the accompanying drawings. In this construction all of the connections are sub-panel connections and the coil adjustments are made from the top of the tube. Desired groups of tube component elements, such as the two shielded triodes and i 5, shown, are inclosed within an evacuated envelope T2 and are provided with usual connection pins, as shown, that extend thru the envelope i2 and a base 13 of the tube. Of these connection pins, an input pin 14 admits signal to the grid of the first triode l0 and an output pin conducts signal from the tube by way of the plate of the second triode 1| (Jo-planar inductance coils l6 and 71 are provided to inductively carry signal from the plate of the triode iii to the grid of the triode H. The coils i6 and 7'! may be multiple layer coils as shown, or may be of a single layer type, as preierred, and are shunted by condensers 6B and 69, respectively. The coils it and T1 are mounted up on depressions in the end wall of the envelope [2 in the bores of which tuning cores I8 and T9 are adopted for axial movement.

In this construction the means for tuning the coils 16' and 11 are available from a single external face of the tube for improved accessibility and ease of tuning. The coils'lb and H are substantially in planar alignment and are permeability tuned by adjusting the iron cores 18 and lil that extend therein by turning the screws 89 and thru the nuts 82 and 83, respectively, throughout, by the use of a screwdriver or other suitable tool.

The construction that is shown in Fig. 3 functions in a manner that is analogous to that of the construction that is shown in Fig. l, with input signal entering the tube thru the grid contact pin 14 and output signal leaving the tube thru the plate output pin 15. The other base contact pins are connected in the usual manner for the circuit components that are involved.

A further modification in the invention is shown in Fig. 4 of the drawings. In this construction the evacuated envelope 85 is divided longitudinally by a metal shield partition 86 to provide an electrical shield between the elements of a heater type multi-grid tube component, such as the pentode 81 that is shown, or the like, and a pair of variable inductance coils 88 and 89 that are co-planar in arrangement and that are available from a single external part, such as the side of the tube as shown, for convenience and ease of adjustment. The solenoids 88 and as preferably are shunted by condensers 92 and 93, respec tively, to aid in tuning the solenoids 88 and 89 where needed.

An insulator is disposed in an aperture in the shield partition 86 for the disposition of a :f connector such as that to the control grid M, or

the like, between the coil 8'3 and the grid 9! of the pentode 81, in usual manner. The shield partition 86 serves the dual functions of providing an electrical shield for the pentode 8'! and the leads to the elements thereof, and, in part at least, to insulate the coils 8B and 39 from excessive heat from the operating temperature of the pentode 81. Thermally insulating material may be added to the partition 85? within the scope of the present invention, if desired. The tube contacts are preferably sub-panel thru a base 94 and are usual for tubes of this character.

The pentode 81 may be replaced, if preferred, with other desired groups of tube elements such as a duo-diode triode or other group of tube elements as needed in a circuit.

The operation of the tube that is shown in Fig. 4 is in conformity with the components that are contained therein, the tuned solenoid 89 receiving signal from the plate of a preceding tube, such as from the plate connection 15 of the tube shown in Fig. 3, or the like, and passing signal by inductance to the tuned solenoid 88. The solenoid 88 feeds signal to the control grid 9! of the pentode 87, the plate of which provides the output from the tube thru the base contact pin that is provided therefor. The pentode 8! preferably is in the tip of the tube so that it is removed from the coils 88 and 89 to minimize the heating thereof. The coils 8B and 89 are installed and tuned as in the construction that is shown in Fig. 3 with the tuning cores disposed in depressions in a side of the tube envelope 25 instead of being in the end thereof.

Another modifications in the present inven tion is shown in Fig. 5 of the drawings. In this construction an evacuated glass envelope 95 if provided with a cylindrical depression 96 extending axially centrally of the tip thereof, as

shown. A washer 91 is secured against a'shoulder in the bore of the depression 96 adjacent the open end thereof. The washer 91, is apertured centrally to serve as a guide for a plunger rod 98 that is adapted for reciprocating therethru under the action of a suitable mechanical means, such as a rack 99, backed by a directing guide I upon the rotation of a pinion IOI for use in rapidly tuning a transformer disposed within the envelope 95 over a wide band of frequencies.

The transformer within the envelope 95 comprises a primary coil or solenoid I02 and a secondary winding or solenoid I03 that are mounted upon the outer wall of the coil supporting depression 96. posed in axially aligned relation with respect to each other and are tuned by a core mounted on the lower end of the rod 98. The solenoid tuning core preferably comprises a pair of substantially conical portions of difierent permeability and inductive characteristics such as a powered iron portion I for maximum inductance at low frequencies and a brass portion I06 for minimum inductance at high frequencies, supported with respect to each other in any preferred manner, as by a portion I01 of fiber, a ceramic, a plastic, or the like, so that the assembled core as mounted upon the lower end of the rod 98 preferably is substantially cylindrical in shape. The composite solenoid core provides the substantially linear inductive advantages of a plurality of different materials in a single core, as it is moved axially of the solenoids I 02 and I03 for the permeability tuning thereof. The primary solenoid I02 may be shunted by a condenser, not shown outside or within the evacuated envelope 95, as preferred, since both its input lead and its plate voltage supplying lead extend to outwardly of the envelope 95.

The secondary solenoid I03 is shunted by a capacitor H0 and has one terminal grounded and its other terminal feeding oscillator impulses thru a condenser III shunted by a resistor II2 to a grid I I3 cooperating with a desired plurality of tube component elements such as the triode shown or the like. The triode plate II4 provides the outlet from the tube thru a base H5.

The operation of the tube that is shown in Fig. 5 is that of a tuned oscillator. The trans- The solenoids I02 and I03 are dis- 2 former, comprising the solenoids I02 and I03, is variably tuned by causing the rotation of the pinion IOI.

It is not intended to limit the present invent on to receiving tubes. It may be embodied also in transmitting tubes or tubes of other types.

It is to be understood that the constructions and the element assemblies that are disclosed herein have been submitted for the purposes of illustrating and explaining suitably operating embodiments of the present invention and that modifications, changes and substitutions of parts therein may be made without departing from the present invention as defined by the appended claim.

What I claim is:

In an electron tube, a rigid envelope surrounding an evacuated hollow space, a plurality of tube elements comprising at least a cathode and an anode mounted on said envelope and within the hollow space, a hollow insulating tube sealed at one end, its open end sealed to said envelope and its sealed end projecting therein, an inductor coil within said envelope and surrounding said insulating tube, a movable core within said tube adjustably positioned to control the inductance of said coil, the position of said core being controllable from without said envelope and a thermal and electric shield positioned within said envelope between said tube elements and said circuit elements.

MYRON T. WILDE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

